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Singlepass aarch64 #2750

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merged 37 commits into from Jan 27, 2022
Merged

Singlepass aarch64 #2750

merged 37 commits into from Jan 27, 2022

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ptitSeb
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@ptitSeb ptitSeb commented Jan 12, 2022

Description

Add Aarch64 support on Singlapass, for both Linux and MacOS.

@ptitSeb ptitSeb requested a review from syrusakbary as a code owner Jan 12, 2022
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@ptitSeb ptitSeb commented Jan 12, 2022

Not ready to merge. Mac support is not here yet.

@ptitSeb ptitSeb requested a review from Amanieu Jan 13, 2022
.iter()
.cloned(),
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@syrusakbary syrusakbary Jan 13, 2022

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Isn't it better to do into_iter() ?

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@ptitSeb ptitSeb Jan 13, 2022

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Sure, I can use into_iter() instead.

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@ptitSeb ptitSeb Jan 13, 2022

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But I'll still need a .cloned() so I think it will not change much in the end.

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@ptitSeb ptitSeb commented Jan 14, 2022

Ready to merge now

ptitSeb added 24 commits Jan 14, 2022
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@Amanieu Amanieu left a comment

I can see a lot of unimplemented!() in machine_arm64.rs. Generally unimplemented! means the same thing as todo!: "this code is not implemented yet but needs to be implemented".

Use unreachable! instead to indicate "I am sure that this code is unreachable". They both panic, but it makes it clearer whether there is still work to be done.

NEON::V31,
];
match n {
0..=15 => Ok(REGS[n]),
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@Amanieu Amanieu Jan 14, 2022

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Typo? Should this be 31? If not then add a comment explaining why.

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@ptitSeb ptitSeb Jan 14, 2022

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Ooops, typo yes.

match n {
0..=31 => Ok(REGS[n]),
_ => Err(()),
}
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@Amanieu Amanieu Jan 14, 2022

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Suggested change
match n {
0..=31 => Ok(REGS[n]),
_ => Err(()),
}
REGS.get(n).ok_or(())

get returns an Option, ok_or converts it to a Result.

But perhaps this function should be changed to use plain indexing and simply panic if an out-of-range value is passed in since you're always unwraping the result anyways.

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@ptitSeb ptitSeb Jan 14, 2022

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it's not happy "expected enum arm64_decl::GPR, found &arm64_decl::GPR"

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@Amanieu Amanieu Jan 14, 2022

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You can used .cloned() to turn an Option<&T> to an Option<T>.


type Assembler = VecAssembler<Aarch64Relocation>;

/// Force `dynasm!` to use the correct arch (x64) when cross-compiling.
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@Amanieu Amanieu Jan 14, 2022

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Suggested change
/// Force `dynasm!` to use the correct arch (x64) when cross-compiling.
/// Force `dynasm!` to use the correct arch (aarch64) when cross-compiling.

if (disp & 0x7) != 0 || (disp >= 0x8000) {
unreachable!();
}
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@Amanieu Amanieu Jan 14, 2022

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Nit: this should use assert! instead.


fn emit_mov_imm(&mut self, dst: Location, val: u64) {
match dst {
Location::GPR(dst) => {
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@Amanieu Amanieu Jan 14, 2022

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Try to encode the immediate as a logical immediate so it can be instantiated with ORR dst, XZR, #imm.

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@ptitSeb ptitSeb Jan 17, 2022

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Yes. also can use MOVN if !val is small enough.
But all this are optimisation that can come later.

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@syrusakbary syrusakbary Jan 17, 2022

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Can we add a todo comment with that suggestion so we log it somewhere?

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@ptitSeb ptitSeb Jan 17, 2022

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The are a few relatively easy optimisation here and there, not just this one (like using LDP/STP more), maybe a notion page?

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@syrusakbary syrusakbary Jan 19, 2022

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Sounds good, let's create a notion doc!

),
}
}
fn emit_add2(&mut self, sz: Size, src: Location, dst: Location) {
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@Amanieu Amanieu Jan 14, 2022

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Can this just be a wrapper over emit_add?

offset: reloc_at as u32,
addend: 0,
});
self.assembler.emit_movk(Location::GPR(GPR::X27), 0, 0);
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@Amanieu Amanieu Jan 14, 2022

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The first one should be movz.


pub struct MachineARM64 {
assembler: Assembler,
used_gprs: HashSet<GPR>,
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@Amanieu Amanieu Jan 14, 2022

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Nit: This should probably be a bitset instead of a hash table.

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@ptitSeb ptitSeb Jan 17, 2022

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Because of the small size of the set? I have use HashSet to be consistant with the x64, that used HashSet too.

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@ptitSeb ptitSeb commented Jan 14, 2022

I can see a lot of unimplemented!() in machine_arm64.rs. Generally unimplemented! means the same thing as todo!: "this code is not implemented yet but needs to be implemented".

Use unreachable! instead to indicate "I am sure that this code is unreachable". They both panic, but it makes it clearer whether there is still work to be done.

I have use unimplemented!() in place where an implementation should exist. At least for the Atomic movement. And I used unreachable!() in place were I didn't expected an implementation to be needed. But I may have letfs some unimplemented!()in wrong places, but I did had the same schema in mind.

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@Amanieu Amanieu commented Jan 14, 2022

I see unimplemented for things like load_address, location_and, etc.

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@syrusakbary syrusakbary commented Jan 27, 2022

bors r+

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@bors bors bot commented Jan 27, 2022

@bors bors bot merged commit cfcc891 into master Jan 27, 2022
14 checks passed
@bors bors bot deleted the singlepass_aarch64 branch Jan 27, 2022
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3 participants